Air and oil preheater



March 1938- J. H. SENGSTAKEN AIR AND OIL PREHEATER Filed May 19, 1934 2 Sheets-Sheet l INVENTOR K m .0 Y

Mam]! 1938 J. H. SENGSTAKEN AIR AND OIL PREHEATER Filed May 19, 1934 2 Sheets-Sheet 2 INVENTOR Joli/1! H. .SE/VG'STH/ffM ATTORNEY Patented Mar. 8, 1938 UNlTE STATES ATE! OFFICE AIR AND 01L PREHEATER.

Application May 19, 1934, Serial No. 726,455

6 Claims.

My invention relates to simultaneouly preheating combustion air and fuel for furnaces.

Many furnace installations now use liquid fuel and many also use preheated air. However, a great many furnaces are precluded from burning the cheaper grades of oil because of the comparatively high viscosity of such oil. The viscosity of such oil can, however, be reduced by preheating.

It is an object of my invention to provide a means and method whereby air and liquid fuel for combustion are preheated to thereby increase the thermal efficiency of furnaces as well as to increase the commercial efficiency of furnaces.

r In accordance with my invention, a heat transferring liquid is passed through a heater having elements in contact with combustion gases from a furnace and then passed through a second heater having elements in contact with air flowing toward such furnace so as to preheat such air.

Also, heat is withdrawn from the circuit which includes said two heaters by oil to be burned in said furnace.

While my invention probably has its greatest field of application in boiler furnaces, I do not limit'myself to its use with boilers, as it is evidently applicable to metallurgical and other industrial furnaces.

In order that my invention may be fully and readily understood, I will now describe in detail and in connection with the accompanying drawings, several exemplifications of my invention selected from a number of possible embodiments thereof. In the drawings,

Fig. 1 is an elevation of a locomotive having my, invention applied thereto.

Fig. 2 is a vertical cross-section through the smoke-box of the locomotive shown in Fig. 1.

Fig. 3 is a fragmentary detail in section of an air heating chamber beneath the fire-box in the locomotive shown in Fig. 1.

Fig. 4 is a detail of the aspirating burner used in Fig. 1; and

Figs. 5 and 6 are fragmentary elevations showing other arrangements for preheating the fuel oil and air for the furnace in accordance with my invention.

The locomotive illustrated in the drawings comprises a boiler I!) having a smoke box l2 within which is an oil heater l4 composed of a number 50 of serpentine coils or units l6 arranged to contact with the hot gases from the fire box 18 of the locomotive after such gases have passed through the flues and/or tubes of the locomotive l0 and thereby been deprived of a large portion of their original heat. To direct the gases against the elements or units of heater Hi, a partition i5 is shown in smoke-box l2 but any convenient means may be used. The heater I l receives oil to be heated through a pipe 20 which delivers into an inlet header 22 to which the units l6 are all connected while the units it deliver the heated oil into an outlet header 24 from which it is conducted by a pipe 26 to the inlet header 28 of an air heater 30 which serves to remove heat from the oil from the heater M and at the same time to preheat air on its Way to the fire box Hi. In addition to the inlet header 28, heater 36 comprises a plurality of serpentine coils or units 32 which conduct the oil from header 28 to an outlet header 34. Oil from header 34 passes off through a pipe connection 36 which delivers most of such oil to the inlet 31 of a pump 38 the outlet 40 of which delivers into the previously mentioned pipe 29.

It will be seen from the foregoing that the coils or units I6 and 32 and the heaters i4 and (ill of which they are parts form portions of a circuit including the pump 38 and pipes 20, 26, and 36 whereby oil may be circulated continuously, or as long as pump 38 is in operation, to first heat the oil in the heater I4 and then partially cool it in heater 30 to thereby preheat air for combustion. However, connection 36 is shown containing a T 42 from which a pipe 44 is taken off to conduct some of the preheated fuel oil to burner 45 which delivers into the fire box I8. The burner lfi may be of the ordinary aspirating type so as conveniently to draw off oil to be burned from T 42. Steam for aspirating oil up to burner 46 is taken from the usual turret by pipe 4'! which extends between the turret and the burner. Connection 36 contains also a second T 48 whereby connection is made between pipe 36 and a pipe 5i! which runs to the tank for fuel oil in the tender 52 of locomotive l0. Fresh oil therefore flows into the circuit of the pump 38 to replace so much as is taken off from such circuit to the burner 46. Pipe 38, however, preferably contains a check valve 5 3 to prevent back flow of oil through pipe 50. It will be understood, that air passing through and over the units 32 of heater 30 does not abstract all the heat from such oil but permits a portion of the heat derived by the oil from the heater Hi to remain in it so that a relatively heavy viscous grade of oil may be used in burner 46 without difficulty. While I have shown the circuit which includes the heaters I4 and 30 as distinct from the tank in the tender 52, I do not limit myself to this, it being within my invention to circulate the oil through such tank, as illustrated in Fig. 5 wherein the pipes 50a, 36a, respectively, Withdraw the cooler oil and return the heated oil to the fuel tank in tender 52. If desired, the piping connected to the pump 38 may include a coil in the fuel tank in tender 52, and in such case it is not necessary to circulate the fuel oil through the heaters l4 and 30, but any convenient fluid such as diphenyl, diphenyl oxide, gas oil, mercury, etc, may be circulated through them instead, as illustrated in Fig. 6 wherein such fluid is circulated through a pipe coil 62 located in the fuel tank in tender 52.

In all of the arrangements shown, except that in Fig. 5, the heat transferring fluid is circulated in a closed path from the outlet'of pump 38 through heaters Hi, 36 and back to the inlet of the pump, the fluid also passing through tank coil 62 in Fig. 6. Although part of the heated oil is withdrawn through pipe -4 to pass through burners 46 and this withdrawal is made up from the tank in tender 52 through pipe 56 in Fig. l, the remainder of the fuel is continuously circulated in the closed path from the discharge side of the pump through the various heaters and back to the inlet of the pump.

While I have described my invention in detail as applied to a locomotive, I do not, in general limit myself to such an arrangement.

It will be seen from the drawings that air for the fire box or furnace l8 may pass into a chamber 56 beneath the fire box l8, such chamber 56 enclosing the heater 3i! and having an inlet for air at its forward end at 5i, and a discharge opening at 58 through which air which has passed over the units 32 may pass up into the fire box l8 adjacent the burner 56. However, I do not limit myself in all cases to details of the arrangement illustrated, even as to the application of my invention to locomotives.

What I claim is:

1. The combination with a furnace of a fluid circuit having a set of heat absorbing elements therein arranged to be contacted by hot gases from said furnace, a set of heat transferring elements in said circuit arranged to contact and heat air passing to said furnace, means for circulating a heat transferring fiuid in said circuit, and means connected to said circuit whereby heat may be withdrawn from said circuit for heating oil to be burned in said furnace.

2. In combination with a locomotive type boiler having a fuel oil burner and a tank containing fuel oil; a fluid circuit having a set of heat absorbing elements arranged to be contacted by hot gases in the smoke-box of said boiler, a set of heat transferring elements arranged in said cir cuit to contact and heat air passing to the firebox of said boiler, means for withdrawing fuel oil from said tank and circulating it in said circuit at a rate greater than it is burned in said furnace, and means connected to said circuit for Withdrawing a portion of said oil therefrom at a temperature above atmospheric and supplying it to said burner to be burned for heating said boiler.

3. In combination with a furnace, and a tank containing fuel oil to be burned in said furnace; a fluid circulating system of the closed circuit type having a set of heat absorbing elements therein arranged to be contacted by hot gases from said furnace; means for circulating a heat transferring fluid in said circuit; a set of heat transferring units in said circuit adjacent said furnace arranged to contact and heat air passing thereto, and means connected to said circuit whereby heat may be withdrawn from said circuit by oil to be burned in said furnace.

4. In combination with a furnace, a fuel oil burner for the latter and a tank containing fuel oil to be burned in said furnace; a fuel oil heater disposed to be contacted by hot gases from said furnace; an air heater arranged to impart heat to air passing to said furnace; a pump for circulating fuel oil through said heaters at a rate greater than it is burned in said furnace; piping connecting the outlet of said pump to said oil heater, said oil heater to said air heater and the latter to said pump so that fuel oil is continuously circulated in a closed path from the discharge of said pump, through said oil heater, said air heater and back to the inlet side of said pump; a branch pipe connecting said burner with said piping for withdrawing part of the heated oil from the latter to be burned in said furnace; and a pipe connecting said tank with the inlet side of said pump for replenishing the oil withdrawn from the piping forming the closed fluid path in which said heater and pump are located.

5. In combination with a furnace, a fuel oil burner for the latter and a tank containing fuel oil to be burned in said furnace; an oil heater disposed to be contacted by hot gases from said furnace; an air heater disposed to impart heat to air passing to said furnace; a pump for circulating fuel oil through said heaters at a rate greater than it is burned in said furnace; piping interconnecting said tank, pump and heaters so that fuel oil is withdrawn from said tank, circulated through said heaters and discharged into said tank; and a branch pipe connecting said burner with said piping for withdrawing a part of the heated fuel oil from the latter to be burned in said furnace.

6. In combination with a furnace, a fuel oil burner for the latter and a tank containing fuel oil to be burned in said furnace; a fluid heater disposed to be contacted by hot gases from said furnace; an air heater disposed to impart heat to air passing to said furnace; a heater in said tank for imparting heat to the fuel oil therein; a pump for circulating a heat transferring fluid through said heaters; piping interconnecting said heaters and pump so that heat transferring fluid is continuously circulated in a closed path from the outlet of said pump through said heaters and back to the inlet of said pump; and means for withdrawing heated fuel oil from said tank and supplying it to said burner to be burned in said furnace.

JOHN H. SENGSTAKEN. 

